The invention relates to a device for monitoring a processing liquid.
From U.S. Patent Document U.S. Pat. No. 5,224,051, a process is known for monitoring a processing liquid. This process is used particularly on a metal processing system, where a plurality of metal processing machines are provided as well as a centrally disposed reservoir which contains the quantity of hydrous cooling lubricant liquid. The metal processing machines are supplied centrally from this reservoir. The cooling lubricant liquid consists of the lubricant and hydrous constituents. These constituents are monitored, and measuring signals are generated which reach an analyzing apparatus. On the basis of the analysis, a modification takes place of the content of a constituent in the monitored liquid.
The process described in the above-mentioned patent shows an apparatus by means of which the content of dissolved oxygen is determined as a reference to microorganisms. Likewise, the conducting capacity, the pH-value and the temperature are determined. However, no information is obtained there concerning the correlation between the oxygen consumption and the microorganism load. It is a disadvantage of this system that a reliable assignment of the measured data to the constituents of the processing liquid cannot be made. For this reason, it is very difficult to meter in additional constituents or to modify the processing liquid.
It is a disadvantage of this known device that certain parameters in the liquid are very difficult to detect. Thus, for example, the detection of the microorganisms contained in the liquid can often be carried out only indirectly. In addition, there is the risk that the measuring signal is mutilated or the operability of the sensor is impaired as the result of suspended solids as well as chemically dissolved substances in the processing liquid.
Furthermore, from German Patent Document DE 43 06 184, a process is known for the continuous detection of physical or chemical parameters of liquids. The publication essentially relates to a valve arrangement which is suitable for the removal or metered addition of liquid. A processing of signal quantities and an analysis of these signals is not found in this publication.
It is an object of the invention to provide a device for monitoring a processing liquid, which is suitable for detecting several constituents in the liquid also under more difficult conditions, that is, also in the case of processing liquids with suspended solids and chemically contaminated processing liquids.
This object is achieved by the invention as described and claimed hereinafter.
The substantial advantage of the invention is the fact that first a device is provided for maintaining the operability of the sensor or sensors. Only when the sensor characteristics are constantly analyzed can informative measuring values be determined. The measuring values reach a device for processing the monitoring signals in order to indirectly or directly from these processed signals influence the composition of the processing liquid.
By means of this device, an optimal stabilization of the processing liquid is achieved and thus a long useful life of this liquid is ensured.
In order to determine the various measurable variables, certain specific sensors are conceivable. For measuring the temperature, for example, a PT 100 sensor is suitable. The concentration of the processing liquid can be determined from the combination of the refractive index and the density or of the UV cloudiness and the density. Foreign oil can also be determined by way of a combination of the refractive index and the density or the cloudiness and the density. Aerobic germs can be determined by way of a corresponding O2-sensor. The pH-value is normally sensed by means of a pH electrode; the conducting capacity is determined by means of a conducting capacity sensor. The corrosiveness of the processing liquid can be determined by means of a redox electrode.
The composition of the processing liquid is influenced, for example, by means of defined control algorithms by means of an expert system or by means of neuronal networks. It is naturally also conceivable to use a fuzzy logic which carries out an optimization operation with respect to the quality of the processing liquid.
The processing liquid is advantageously monitored in a processing tank. This monitoring can be carried out, for example, by a mobile servicing apparatus suitable for field use. Naturally, variants of the apparatus are conceivable, such as a partially mobile apparatus which supplies the detected data to a remote diagnosis.
In accordance with one embodiment of the invention, the processing liquid is monitored in one or several processing tanks. It is also possible to arrange tanks side-by-side with a processing tank in order to ensure particularly favorable environmental conditions there. Advantageously, sensors can be used which sense the loading of the processing liquid with suspended solid particles. In addition, it is expedient to detect the microorganisms, the pH-value or the corrosiveness, or additional relevant quantities, such as germs, yeast fungi, bacteria, abrasiveness, nitrate, nitrite, water hardness, interfering ions, dispersed air, foam, foreign oil, foreign substances, temperature, conducting capacity in the processing liquid.
It is an object of a further refinement of the invention to carry out a remote data transmission. By way of this remote data transmission, for example, by way of a corresponding modem, monitoring signals are supplied to one or several devices for the purpose of an analysis. An integrated data analysis is also conceivable.
In addition to the device for monitoring the process liquid, an advantageous embodiment of the invention provides a filtering system for a mechanical purification. This filtering system consists, for example, of a band pass filtering system or a vacuum filter as well as additional suitable systems/apparatuses and peripheral devices.
If the processing liquid must be separated into specific constituents, for example, for the purpose of disposal, a system may be provided in another embodiment of the invention which, for example, carries out an emulsion separation. Such systems normally operate on a membrane basis (ultrafiltrate) or on a thermal or chemical basis.
An important building block in the device for monitoring processing liquid is the sensing of an aerobic infestation. The latter correlates with the oxygen consumption in the processing liquid. The oxygen consumption caused by aerobic germs is directly related to the germination index (microbiologically expressed in column-forming units per milliliter). However, the oxygen consumption in the case of a given constant aerobic germ involvement is a function of the temperature. It is therefore useful to determine the correlation between the oxygen consumption, the germination index and the temperature. Naturally, the oxygen consumption can be determined only in a closed system. It is therefore necessary to feed the processing liquid separately to a testing tank and to carry out the measuring of the oxygen consumption there.
These and other features of preferred embodiments of the invention are found, in addition to the claims, in the description and the drawings, in which case the individual features can be implemented separately or combined in the form of subcombinations in the embodiment of the invention and in other fields and can represent advantageous embodiments which are patentable by themselves, for which protection is claimed here.
The invention will be explained in more detail hereinafter with reference to a embodiment.